fix MACBase: wrong init stage
sendSync: added InetSimpleModule with sendSync() implementation
sendSync: let everything subclass from InetSimpleModule
sendSync: replace send() with sendSync() everywhere except when sending to channel (PPP, EtherMAC, etc)
sendSync: fix EtherLLC - emit after sendSync is forbidden
sendSync: hack: work around Ieee80211Mac crash (now leaks msg!)
sendSync: Ieee80211Mac: temp hack for sendSync
TCPGenericCliAppBase generalized and renamed to TCPAppBase

The only GenericAppMsg reference in it was in sendPacket(),
the rest of the code can be reused for other kind of TCP apps too.